The present invention relates generally to a door which is used to gain access to the interior of a steam generator and its related equipment, and more particularly to a door latch which can be quickly released by a person from within the steam generator or related equipment.
Access doors for steam generators and related equipment (e.g., flues, ducts, windboxes, hoppers, air heaters, penthouses, vestibules, precipitators, baghouses, scrubbers, etc.) are used to gain entry into the interior of the steam generator apparatus and related equipment. Installation and maintenance personnel need such access for movement of equipment and materials into and out of the steam generator and related equipment for installation, repair, and maintenance of the internal components and surfaces of the steam generator and related equipment.
The prior art steam generator access door constructions are not known to have been equipped with latch mechanisms which can be unlatched from within the steam generator.
The lack of providing steam generator access doors with a latch mechanism which is releasable from the inner side of the door has been due, in large part, to the harsh operating environment caused by the high temperature combustion product laden flue gas flowing through steam generators firing coal and other fossil fuels. These flue gases contain entrained products of combustion such as slag, ash, and/or soot which are deposited on the exposed surfaces of the steam generator.
A variety of latch mechanisms which can be released from the inside of a door have been provided for freezers, refrigerators and the like, where the interiors are kept under a relatively clean environment. Such latch mechanisms are of multipart construction whose parts are automatically returned to the normal operative position after the door has been opened from the inside. See for example, U.S. Pat. Nos. 2,747,906; 2,849,250; 2,966,864; 3,936,086; and 4,372,591.
Prior art latches which allow the opening of an access door from the indoor side are complex in construction and operation and may be difficult to manipulate in the dark and cramped quarters of a steam generator.